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Fix T44113: Ashikhmin-Shirley distribution of glossy shader at 0 roughness causes artifacts when background uses MIS 

Was a division by zero error, solved in the same way as beckmann/ggx
deals with small roughness values.
This commit is contained in:
Sergey Sharybin 2015-04-01 14:21:21 +05:00
parent 71af08e1c9
commit af399884e1
Notes: blender-bot 2023-02-14 09:20:15 +01:00 
Referenced by issue #44113, Ashikhmin-Shirley distribution of glossy shader at 0 roughness causes artifacts when background uses MIS
1 changed files with 12 additions and 2 deletions
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14
intern/cycles/kernel/closure/bsdf_ashikhmin_shirley.h
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@ -69,6 +69,9 @@ ccl_device float3 bsdf_ashikhmin_shirley_eval_reflect(const ShaderClosure *sc, c
float out = 0.0f;
if(fmaxf(sc->data0, sc->data1) <= 1e-4f)
return make_float3(0, 0, 0);
if(NdotI > 0.0f && NdotO > 0.0f) {
NdotI = fmaxf(NdotI, 1e-6f);
NdotO = fmaxf(NdotO, 1e-6f);
@ -190,8 +193,15 @@ ccl_device int bsdf_ashikhmin_shirley_sample(const ShaderClosure *sc, float3 Ng,
/* reflect I on H to get omega_in */
*omega_in = -I + (2.0f * HdotI) * H;
/* leave the rest to eval_reflect */
*eval = bsdf_ashikhmin_shirley_eval_reflect(sc, I, *omega_in, pdf);
if(fmaxf(sc->data0, sc->data1) <= 1e-4f) {
/* Some high number for MIS. */
*pdf = 1e6f;
*eval = make_float3(1e6f, 1e6f, 1e6f);
}
else {
/* leave the rest to eval_reflect */
*eval = bsdf_ashikhmin_shirley_eval_reflect(sc, I, *omega_in, pdf);
}
#ifdef __RAY_DIFFERENTIALS__
/* just do the reflection thing for now */